The role of gallium in CuInSe/sub 2/ solar cells fabricated by a two-stage method

Abstract

Incorporation of Ga in CuInSe/sub 2/ thin film solar cells formed by a two-stage method results in improved adhesion between the CuInSe/sub 2/ absorber layer and the Mo back electrode. The original intent of incorporating Ga was to increase the bandgap by forming a homogeneous CuIn/sub 1-x/Ga/sub x/Se/sub 2/ quaternary absorber. Rather than the expected increase in bandgap by uniform substitution of Ga for In, adhesion was improved by the formation of a Ga-rich interfacial layer between the absorber and the molybdenum. In addition to improved adhesion, an increase in efficiency due to improved open circuit voltage was observed. Structural models for the absorber layer are proposed based on Auger analysis and solar cell performance data. >